Alloy and process of heat treatment



Patented Oct. '22, 1929 UNITED STATES PATENT OFFICE MICHAEL. G. CORSON, OF JACKSON HEIGHTS, NEW YORK, ASSIGNOR TO ELECTRO METALLURGICAL COMPANY, A CORPORATION OF WEST VIRGINIA ALLOY AND PROCESS OF HEAT TREATMENT" N Drawing.

This invention relates to the production of hard and strong alloys containing copper and nickel as the principal constituents. It comprises the addition of silicon in regulated amounts to such alloys to impart to them the ability to assume a hard and strong condition upon suitable heat treatment. The invention also comprises the application of cer= tain processes of heat-treatment to such silicon-containing alloys to bring out the hardening eifect of the silicon addition.

In my copending application Serial No. 58,636, filed September 25, 1925, I have disclosed that copper and copper. alloys containing regulated minor amounts of one or more of certain silicides, among them nickel silicide, Ni Si, will assume a remarkably hard and strong condition if subjected to certain heat treatment. I have also disclosed in the above-mentioned application that nickel may be present in excess of the amount required to combine with the silicon present in the alloy, and that copper-nickel alloys containing as high as 40% nickel can be hardened by heat treatment after a content of silicon has been incorporated. I have now discovered that copper-nickel alloys containing up to80% and more of nickel and appropriate amounts of silicon are susceptible to hardening when heat-treated as hereinafter described.

My invention is of particular applicability in treating copper-nickel alloys having compositions within the range of those which are known commercially as Monel metal compositions. For example, an alloy containing about 7 0% nickel and about 3.5% silicon, with the balance principally copper, is hot rolled and then quenched from above 900 C.

40 In the quenched condition the alloy is very soft,having a hardness of 95 Brinell,--and can be cold worked in any suitable way. The alloy either as quenched or after further working is then subjected to a second heat treatment of the type commercially known as ageing or age-hardening, which comprises holding the alloy at a temperature of from 500 C. to 700 C. for a period of from one hour to twenty-four hours depending upon the temperature at which the heat treat- Application filed November 19, 1926. Serial No. 149,526.

It is found that the percentage of silicon required to render the alloy susceptible to hardening by heat treatment varies somewhat with the proportions of nickel and copper. Also the amounts of silicon which can be added Without rendering the alloy unworkable vary over a considerable range roughly in proportion to the amount of nickel present in the alloy. To be specific, copper nickel alloys having a nickel content around the lower limit of the range specified, namely 40%, become susceptible to a hardening heat treatment when 1.5% silicon is present and remain fully workable until 4% or more of silicon is added, whereas those alloys having a nickel content of 70% and more become heat hardenable when 2.5% silicon is present and do not become unworkable by rolling or drawing until approximately 10% silicon is added. In the foregoing specific examples, the ratio g; 5:322:22: falls within the range 7 to While the process of heat treatment has been described with particular reference to its use in treating a specific alloy, it is to be understood that it may be applied to any of the alloys falling within the range outlined. The various factors appertaining to the heat treatment such as temperature and'duration of the heat treatment also may vary somewhat from the range above set forth without departing from the invention.

What I claim is: 1. An alloy comprising nickel 40-80%, silicon 1.540%, balance principally copi percentage Si percentage within the range 7 to 28 2. An alloy comprising approximately 70% per, with the ratio alling nickel, 3.5% silicon, balance principally cop- 3. An alloy comprising approximately nickel, 2.510% silicon, balance principally copper.

4. The alloy comprising nickel 4080%, silicon 1.540%, balance principally copper, Ni percentage Si percentage the range 7 to 28, and having such structure, hardness, and other properties as are produced in an alloy of said composition by guenching from a temperature of above 900 and ageing at a temperature between 500- 700 C.

5; An alloy containing approximately 70% nickel, 2.510% silicon, balance principally copper, and having such structure, hardness,

with the ratio falling Within and other properties as are produced in an alloy of said composition by quenching from a temperature above 900 C. and ageing at a temperature between 500700 C.

In testimony whereof I aflix my signature.

MICHAEL G. CORSON. 

